This book seeks to explain how Jacques Lacan was influenced by Martin Heidegger's thought during the second half of the 20th century. In our proposed reading, the psychoanalyst addresses the following questions: How does truth occur in line with the manifestation of being? How to think the essence of man in ek-sistency as ek-sistency? In this path of elaboration, the works of Hegel, the young Marx, Lévi-Strauss, Saussure and Jakobson emerge as main references. We try to show how the psychoanalyst seeks to capture the 'real', the traumatic that insists on not being recognised, so that the crossing of anguish, from the praxis of coming across this plane that is usually avoided, allows the Being to manifest itself.